Israel's military declined to comment, as did the foreign ministry and the prime minister's office

Syrian officials have also not commented.

An earlier Russian statement said they had also "detected rocket launches from the French frigate Auvergne."

France denied any involvement in the aircraft's downing.

Foreign powers backing different sides in Syria's war often use hotlines to try to ensure they do not accidentally attack each another - but the risk remains high.

Russia's military has been supporting Syria's President Bashar al Assad since late 2015, but it has come at a cost with a number of fatal air incidents.

In March 2018, 39 people died when a Russian transport plane crashed while coming in to land at the Hmeimim base; and in December 2016 a TU-154 on its way to Syria crashed, killing 92 people including army musicians and dancers.